Leather-like material and process of making same



Patented J uly 7, 1925.

UNITED STATES I 1,544,744 PATENT OFFICE.

WILLIAM E. GWALTNEY, WILKINSBURG, PENNSYLVANIA, ASSIGNOR TO SYNTHIDE PRODUCTS COMPANY, A CORPORATION OF DELAWARE.

LEATHER-LIKE MATERIAL AND PROCESS OF MAKING SAME.

No Drawing.

To all whom it may concern:

Be it known that LWVILLIAM E. GWALT- NET, a citizen of the United States, residing at Wilkinsburg, in the county of Allegheny and State of Pennsylvania, have invented certain new and useful Improvements in Leather-Like Materials and Processes of Making Same, of which the following is a specification.

This invention relates to the manufacture of a synthetic product derived from cotton or similar vegetable fiber, and having the appearance, texture and essential qualities of leather. The invention includes the process of making the said material, and also the synthetic product having the qualities above mentioned.

Essentially my process consists in acting.

upon fibrous cellulose with a solution having a solvent action upon cellulose, said so lution preferably also carrying cellulose in solution, the treatment being so limited and carried out in 'such manner as to conserve, to a greater or less degree, the fibrous structure of the undissolved cellulose. Preferably the original, fibers, (and also of course the modified or residual fibers resulting from the above treatment) are so laid as to intersector interlace with each other in planes approximately parallel to the surfaces of the sheet or article. The fibrous 'sheet thus prepared is then impregnated with a colloidal binding substance which is either insoluble in water, or alternatively is rendered insoluble by subsequent treatment analogous to the known tanning, tawing or similar operations applicable to natural leather. The product so prepared is a fibrous sheet, not

tough, opaque, pliable,

and having the essubject to putrefaction, sential qualities and characteristics leather made from hides. Its visual resemblance to leather may be further increased i desired by certain superficial treatments as of viscose.

Application filed March 8, 1921. Serial No. 450,719.

substituted for those of the insolubilized glue ferred embodiment of the invention .1 use what ma be termed a bat of felted or interlacing ce lulose fibers, such as cotton, ramie, etc. Such a bat may be prepared by card. ing cotton fiber and then combing or blow- 1ng it cross-wise as it comes from the cards. The result of this treatment is a felted bat in which the fibers interlace or intersect 1n planes approximately parallel to the surfaces.

This bat is then exposed to the action of a strong viscose-forming solution, to which is preferably added a relatively weak solution These solutions may be separately prepared, but are preferably .made

ed into a viscose solution or dispersion by any known or appropriate method, such as the caustic soda and carbon disulfid method. Caustic soda (about 150 kilos) is then dissolved in about 27,000 kilos of water and when cold about 110 kilos of carbon disulfid are added with vigorous stirring and the mixture is added to the viscose solution un-- til the mixture contains 2 of viscose. This proportion of viscose may, of course, be varied within wide limits, in accordance with the character of the final product desired. The presence of this dissolved viscose, though not essential, is advantageous in that it serves to maintain the integrity of the bat during the subsequent manipulations. The above viscose-forming solution, preferably carrying dissolved viscose, is applied to the cotton bat in any suitable manner as by rolls, from which the bat, now thoroughly saturated or impregnated with the solution may be delivered onto'an endless belt f upon which air drying-of the saturated-bat is effected. The bat is then passed over steam heated drums, maintained at about 100 (1., until thoroughly dried. The effect of the viscose-forming solution on the cellulose fiber bat is to convert the fibers wholly or partly into viscoid, without disintegrating or wholly destroying the fibrous structure.

The viscoid bat is then, preferably, subjected to the action of an excess of dilute sulphuric or other acid to remove the alkali and also to convert any unchanged cellulose into the hydration product known as celloby the following process About 45 kilos of carefully cleaned cotton fibers are convertbiose. The acid-treated bat is then neutralized, thoroughly washed and dried.

The resulting bat possesses suflicient strength to permit of mechanical handling, and is next impregnated with a colloidal binder: for this purpose I may use glue or gelatin, but I prefer to use the special binder compound hereinafter disclosed.

After the but has been thoroughly salurated with the binder compound it is run between squeeze rolls to remove excess binder. If it is desired to render the product flame-proof or fire-proof, I may add suitable fire-retarding components to the binder, such for example as a mixture of ammonium chlorid and zinc chlorid rendered ammoniacal with aqueous ammonia. The binder-saturated bat, may then, if desired, be napped up on one side by a napping machine to give it the appearance characteristic of the flesh side of a hide. In like manner I may strike back across the grain surface with a stiff brush, thereby removing the superficial binder, slightly raising the nap of the fibers, and imparting to the sheet, after calendering, the appearance of grained leather.

The bat thus prepared is then subjected to any suitable tanning, tawing or analogous operation applicable to natural leather, but preferably tawing by means of solutions of chrome salts such as chromium oxychloride. Following this treatment, it is preferably moistened with warm water and permitted to cure for one or two days.

My preferred binder compound comprises in addition to glue, a softening agent such as glycerine or glycol; an antiseptic material such as boric acid or benzoic acid; a hygroscopic salt such as sodium acetate; and a texture modifying component, preferably a low-melting point paraffin, such as paraffin wax (melting 'point 44 C.), ozokerite, petroleum jelly or the like.

For example :A mixture of water (250 parts by weight), glycerine (50 pts.), powdered borax (2 pts.), and acetic acid (2 pts.) is heated to boiling in a steam kettle whereupon there is added 2 pts. of paraflin wax (melting point 44 (1). After this mixture is thoroughly melted there is added with constant stirring 100 pts. of glue. The

mass is heated and stirred until the glue has passed into solution and the whole is thoroughly homogeneous, water being added if necessary to restore the original volume. If desired to form a harder setting com pound, hardening components may be added such for example as 50 parts of granulated sugar or the same quantity of soap. The

hardening may be controlled by the use of a softening agent, such as glycerine. The

composition is then permitted to cool and to age by standing a sufficient period, say about 48 hours,. The resulting composition has many advantageous properties and is I believe a novel composition of matter, applicable for use in other relations than that herein described, such forexample as for printing rolls. y

In order to apply the binder, it is melted at a temperature not exceeding 54 0., at which temperature it will be found to be quite fluid. Substantially higher temperatures will tend to destroy the binding properties of the compound.

It will be understood that the composition mentioned above may be variously modified Without departure from my invention. For example additional mechanical strength may be imparted to it by adding a rubber mixture prepared by macerating 454 grams of pure gum rubber with five kilos of a suitable solvent, such as carbon disulfid or benzol, until the rubber is dissolved; and then adding one gram of flowers of sulfur,

or an equivalent amount of sulfur chloride,

to each 500 c. c. of the solution. After thoroughly mixing this compound is incorporated with the glue while stirring the compound, any excess heating being avoided. hen this rubber addition is used, the sheet is preferably first tanned as described above, and thereafter heated to a relatively high temperature, say about 120 C.

The tanned material may then be finished by any of the methods commonly applied to the finishing of leather made from hide.

The product prepared as described herein has the advantage over natural leather that it can be made in wide strips of considerable length, and, within limits, of any desired thickness: it is moreover far more uniform in quality than natural leather, which. as is known varies greatly according to the part of the animal from which the hide is taken. The product is also much stronger than leather of equal thickness, has better Wearing qualities, is highly pliable and flexible, and will not harden or crack when wetted and dried.

I claim 1. Process of making a leather-like product comprising subjecting a bat of interlaced cellulose fibers to the action of a solution of the xanthate or viscose type having a solvent action upon cellulose while conserving the fibrous structure of the cellulose; and impregnating the resulting sheet with a water insoluble colloidal binding material.

2. In a process of making a leather-like product, the steps comprising forming a bat of interlaced cellulose fibers, and subjecting the same to a solution having a solvent action upon cellulose while conserving the fibrous structure of the cellulose.

3. Process according to claim 2, wherein a cellulose solvent of the xanthate or viscose type is used.

4. Process of making a leather-like product,

.comprising subjecting a bat of interlaced cellulose vent action upon cellulose while conserving the fibrous structure of the cellulose; im-

fibers to a solution having a solpregnating the resulting sheet with a colloidal binding material comprising glue; and insolubilizing the binder by a treatment analogous to tanning.

, 5. Process according to claim 4 wherein the cellulose solvent contains also dissolved cellulose.

6. Process according to claim 4 wherein a cellulose solvent of the xanthate or viscose type is used. v. p i

g 7. Process according to claim 2 wherein the cellulose solvent contains also dissolved cellulose.

8. A tough, pliable, opaque, fibrous, nona water-insoluble colloidal binding ma.-

terial.

9. A tough, pliable, opaque, fibrous, nonputrifyin material comprising interlaced cellulose bers modified by treatment with a cellulose solvent and bonded together by an insolubilized colloidal binding material.

In testimony whereof, I afiix my signature.

WILLIAM E. GWALTNEY. 

